An FePt alloy can be provided with the fct (Ordered Face Centered Tetragonal) structure which has high crystal magnetic anisotropy by heat-treating at an elevated temperature (for example, at 600° C. or higher), and therefore an FePt alloy has been highlighted as a magnetic recording medium. To make FePt particles smaller and more uniform in the thin film of the FePt alloy, it is proposed that a predetermined quantity of carbon (C) be included into the thin film of the FePt alloy (for example, Patent Literature 1).
However, the formation method of the FePtC thin film, described in the Patent Literature 1, is the method of vapor-depositing Fe, Pt, and C simultaneously on an MgO (100) substrate by using the Fe target of a 2-inch diameter, C target of a 2-inch diameter, and the Pt target of 5 mm in height and width. In this method, it is difficult to obtain the film whose composition is controlled strictly. Additionally, three targets are required and each target needs a cathode, a power supply, etc, and so the cost of equipment becomes high while the preparatory work of sputtering takes time and effort.
It is thought that an FePtC thin film found by the process for forming an FePtC thin film described in Patent Literature 1 has a granular structure in which FePt alloy particles are separated by partitions of C, thereby allowing the FePtC thin film to exhibit magnetic recording characteristics. However, when the partitions of the granular structure were formed only of C (carbon), a carbon phase 14 grew to surround FePt alloy particles 12 growing on a substrate surface 10A of a substrate 10, for example, as illustrated in FIG. 1. This sometimes prevented the FePt alloy particles 12 from growing vertically onto the substrate surface 10A so that a plurality of the FePt alloy particles 12 were deposited vertically onto the substrate surface 10A (for example, Non-Patent Literature 1). When a plurality of the FePt alloy particles 12 are deposited vertically onto the substrate surface 10A, the obtained thin film may have deteriorated characteristics as a magnetic recording medium, or may be useless as a magnetic recording medium.
In order to suppress the phenomenon that a plurality of the FePt alloy particles 12 are deposited vertically onto the substrate surface 10A, metal oxides such as Ta2O5 and TiO2 may be effectively used instead of C to form the partitions of the granular structure, which is disclosed in Non-Patent Literature 1.